Butt seal for miniature lamps



July 28, 1925. 1,547,748

J. c. GROGAN BUTT SEAL FOR MINIATURE LAMPS Filed May 5, 1921 iNVENTOR JHCOB c. GEOq'fi/V ATTORNEY Patented July .28, 1925.

UNITED STATES 1,547,748 PATENT OFFICE.

JACOB C. GEOGAN', OI" NEWARK, NEW JERSEY, ASSIGNOR TO WESTINGHOUSE LAIP COH PANY, A CORPORATION OF PENNSYLVANIA.

[BUTT sm 'roa MINIATURE LAMPS.

Application 'flled Kay 5,

To allwhom it may concern:

Be'it known that I, Jacoa C. GROGAN, a citizen of the United States, and a resident of Newark, in the county. of Essex and 6 State of New Jersey, have invented a new and useful Improvement in Butt Seals for Miniature Lamps, of which the following is a s ecification.

his invention relates to the glass work- 10 ing art and, more particularly, it relates to butt sealing of glass parts, as practiced in the manufacture of incandescent electric lamps.

One of the objects of this invention is to 1 provide a novel method of uniting th ends 'of lass parts and to include, in the seal per ormed thereby, one or more electrical conductors.

Another object of this invention is to pro- 2 vide a method of sealing electrical leadingin conductors between the ends of two glass portions of an incandescent lamp, whereby the mass of glass wetting with the conductors is increased and whereby a substantially 2 non-leaking seal is obtained, thereby reducing losses due to faulty seals.

Other objects of thisinvention will be apparent from the following description.

The accompanying drawin which form a part of this specificati0n,'il ustrate a lamp in various stages of manufacture, and, in these drawings Fig. 1 illustrates parts of a lamp, as assembled for the sealing-in operation by the old method,

Fi 2 illustrates parts of a lamp assemb ed for the sealing-in operation by the new method,

Figs. 3 and 4 illustrate the formation of the seal in successive stages of manufacture and, V

Fig. 5 illustrates a completed seal with leading-in conductors sealed in position.

In the manufacture of incandescent electrio 1am s, it has been found desirable to have eac manufacturing step or operation fully and satisfactorily completedin order that the operations fol owing will not prove abortive by reason of defects inherent in one of the earlier operations. In theimanufacture of certain incandescent lamps, such, for instance, as miniature lamps of the tipless type, one of the operations provides for the scaling to ether of two hollow portions of glass whic have been assembled with 1921. Serial no. 487,077.

their openings in register. This operation provides for the inclusion of metallic conductors for carrying electric current from the exterior of the lamp to the filament. In forming the seal, the leading-in conductors are heated conjunctively with the heating j of the glass. The method of heating, as heretofore performed, has been destructive to the portions of the leading-in conductors which are embedded in the glass forming the seal as these portions have had their surfaces subjected to the heating fires. This destruction of the conductors prevents them from properly wetting with the glass and making a gas-tight seal.

The new method of sealing together two arts of an incandescent lamp, with leadmg-in conductors properly embedded in the seal, will. be described in connection with the formation of a seal between a lamp bulb and a tube of a miniature lamp of the tipless type. It is to be understood, however, that the method is not limited in its application to miniature lamps but may be employed in making other types of lamps, or In joinin parts of vitreous material together and aving metals or other bodies embedded in the joint.

The invention will be more readily appreciated by first settin forth a short description of the old met 0d of forming the seal. In Fig. 1 is illustrated a bulb 10 of a miniature lamp and a short length of tubing 11 positioned apart from the bulb although having its opening substantially in alignment with the opening in the bulb. A mount, which usually comprises leadin in conductors 12, a glass bridge 13 for positioning the conductors and a filament 14 attached to the short ends of the'conductors, is (positioned in the bulb so that the free an s of the conductors hang over the edge ofthe opening in the bulb.

The glass of the bulb 10 and tube 11 is brought to a plastic condition by first di- I recting the flame from burners 15 to meet substantially in a vertical axis passin through the opening in the bulb and the opening in the stem. The bulb is moved to a position so that the opening edge thereof is in contact with the flame and is thus heated.

It is to be noted that, during the heating, the flame plays directly upon those portions of the leading-in conductors which are to be embedded in the seal. During the heating of the bulb, the stem is maintained in a position above the flames, as illustrated in dotted lines in Fig. 1. The second step of this old method provides for the movement of the tube toward the bulb but not into contact therewith or with the leading-in conductors but to the position illustrated 1n full lines in Fi 1. During the heating of the tube, the ame still continues to play directly uponthe leading-in conductors.

,When the proper plasticity of the lamp parts'is obtained, the tube is pressed against the bulb and in contact, for the first tlme, with the leading-in conductors. The direct application of fire to the leading-in conductors burns ofi any flux on their surfaces and, in most instances, partially destroys the metal of the conductors to an extent that makes the seal entirely worthless, on ac-' count of air leaks. If, for instance, .dumet wire, which is usually rovided with a coating of copper-borate ux, is employed it is found that the seal between the leading-in wires and the glass is not satisfactory as, apparently,the copper borate is burned from the leading-in conductors and, apparently the copper sheath is punctured. This defeet results in the formation of a leaky seal and, therefore, an unsatisfactory manufactured lamp.

By the present method of making a gastight seal between the lamp parts it is preferred to indirectly heat those portions of the leading-in conductors which are to be incorporated in the seal and thus prevent the fires from playing directly thereon.

Referring to Fig. 2, the mount and the portions of the lamp to be sealed together are assembled as illustrated, having the electrical conductors 12 in contact with both the bulb l0 and the tube 11 while the latter members have their adjacent edges registering with each other. The bulb and tube may be heated to lastic condition by any desired means, as, or instance, by applying pointed flames or fires which are preferably irected to the base of the tube. In practice, the flames are flared against the bulb and tube to simultaneously heat the edges thereof, but they do not, however, make direct contact wit those portions of the leading-in conductors which are to be embedded in the seal. Therefore, any flux which may be on the conductors is not burned off by reason of the excessive heat due to the flames playing directly on the conductors. In the case when dumet wire is em loyed for the leading-in conductors, the iihx carried thereon and the copper sheath thereof are.

not destroyed or punctured by the direct application of heat. Thus, certain portions of the conductors, a proper .wetting of the leading-in conductors with the glass takes place uring the formation of the seal.

by protecting mamas After the tube and bulb have been properly heated, preferably by creating a relative movement between the fires and the lamp parts to obtain a circumferential heating, the tube and bulb are forced into intimate contact to properly embed the leadingin conductors. The usual-method of providing the relative movement between the fires and the lamp parts is to rotate the bulb and tube in an assembled position. v

The pressing of the bulb and the tube toether forms an enlargement or ring 16, as illustrated in Fig. 3. The ring 16 is generally of greater diameter than the diameter of the tube or of the top of the bulb, as a relativelylarge mass of glass collects at this region because of puddling of the glass dur-- ing the heating. Puddling of the glass provides greater contact surface for embedding the leading-in conductors.

After the tube and bulb have been pressed together, the fires are preferably maintained for a short time to bring the glass ofvthe seal and that contiguous thereto to a substantially uniform temperature. The attainment of this substantially uniform temperature reduces a uniformity of plasticity of the g ass forming the seal and the adjacent portions of glass. Following the forming of the seal, the rotation of the work is stopped.

The mount is then aligned, if necessary, in the bulb so that the filament is held substantially in the center thereof. During the time required to align the filament, the heated. portion of the glass becomes substantially uniform in temperature thus permitting the usual pulling operationfor reducmg the quantity of glass in the region of the seal. and for forming a. constriction 17 in the tube 11: for the purpose of sealing off the lamp during the exhausting operations.

In, practicing the invention. in accordance withthe above description, there is a reduction in the number of lamps having faulty scale. The main reason for this increase of efiiciency is that a satisfactory wetting of the glass and the leading-in conductors has been obtained.

From the foregoing description, it will be seen that obtain a satisfactory seal chiefly by protecting from the fires the portions of the leading-1n conductors which are incorporated into the glass seal. It is, therefore, desired to be understood that any means for accomplishing this purpose which may be a modification from that set forth and coming within the terms ofthe a pended claims is regarded as being within t e scope of the invention.

What is claimed is:

1; The method of butt sealing two tubular bodies and embedding a third body in the seal thereof which comprises itioning said tubular bodies with an end 0 each part separated by and in contact with said third to unite an embed said third body within the joint and exerting pressureto enlarge said joint. v

2. The method of preventing injurious application of heat to leading-in conductors Y during the butt sealing of the ,com nent parts of an incandescent lamp whic 'comprises positioning the ends of tubular glass parts in contact with leading-in wires placed therebetween and rendering ad'acent portions of said. glassparts plastic y fires impinging only upon the outer cylindrical surfaces of at least one of said parts and effecting a relativecmovement of said tubular glass parts to unite the same vat the plastic rtion.

3. The method of butt sealing the component parts of an electric incandescent lamp, which comprises, positioning a conductor with a portion thereof in contact with the ends of two lamp parts, applying heat to said parts adjacent said conductor, said adjacent parts being disposed to directly receive heatand prevent injurious heating of the conductors disposed therebetween, pressing said parts to ether to enlarge the diameter of the heate portions and permitting them to unite with the leading-in conductors embedded in enlargement.

4. The method of butt sealing the com.- ponent parts of an incandescent lamp which consists in assembling a tube in alignment with a; bulb having a. mount ther'ein and with the leading-1n conductors of said vmount positioned between and. in contact with ends of said bulb and tube, heating the bulb and tube in amanner to prevent 1njurious application of heat to portions of the leading-in conductors between said tube and bulb, pressing the tube and bulb together to rovide a thickened portion at the point 0 union and embedding said leading-1n conductorsin said thickened portion.

5. The method of forming a butt seal in an incandescent lamp which consists in positioning the leading-in conductors of a -mount in contact with and between theends of a bulb and a tube, locally heating portions of the bulb and tube adjacent the conductors and forcing the heated portions of the bulb and tube mto a thickened portion having intimate contact with said conductors.

i 6. The method of butt sealing component parts of an incandescent lamp which consists in inserting a mount in one part with the leading-in wires thereof in contact with an edge of said part, placing another part in contact with leading-in conductors of sa-idmount, applying heat to portions of said .lamp-partsadja'cent to the leading-in conductors until said portions are rendered plastic, ressing the parts to produce a thickene portion'to'form a seal with the leading-in conductors embedded therein.

7. Themethodof forming a butt seal in a miniature incandescent electric lamp which consists in ositioning portions of the leading-in con uctors of "a mount in contact with a tube having one of its ends registering with and in close roximity to the open portion ofa lam bul applying firesto 10- call heat the g ass of said tube andbulb, sai tube serving as a shield to prevent direct. application of heat to said portions of the con uctors, creating a relative movement between said; fires and said lamp-7., parts, pressing the glass of the bulb and tube together and around said conductors and drawing said glass before it has cooled to such a temperature as tobe unworkable.

In testimony, whereof I- have hereunto subscribed my: name this 30th day of April, 

